A few weeks ago i had a coil pack go on my car and had to be recovered. I had the coil pack replaced but since my car asn't run properly. The mechanic say the air value was worn and not working properly so i had it replaced. Now it running a bit better but still not right. It judders as you accelerate and looses power on the pull of. If i paid to have it put on a diagnostic machine, would it tell me exactly whats wrong with the car ?